Method and apparatus for transmitting and receiving uplink channel sounding reference signals in a wireless communication system

ABSTRACT

A method is provided for transmitting uplink control information by a terminal in a cellular communication system. The method includes receiving system information associated with uplink transmission of a Sounding Reference Signal (SRS) from a base station; determining an orthogonal sequence having a first length or a second length predefined; transmitting uplink control information to which a first orthogonal sequence is applied, if the first orthogonal sequence having the first length is determined; and transmitting uplink control information to which a second orthogonal sequence is applied, if the second orthogonal sequence having the second length is determined. The SRS is selectively transmitted with the uplink control information, based on the received system information, and the uplink control information, to which the first orthogonal sequence having the first length is applied, is transmitted regardless of whether or not the SRS is transmitted in a corresponding slot.

PRIORITY

This application is a Continuation of U.S. application Ser. No.12/110,828, which was filed in the U.S. Patent and Trademark Office onApr. 28, 2008, and claims priority under 35 U.S.C. §119(a) to a KoreanPatent Application Serial No. 2007-41645, which was filed in the KoreanIntellectual Property Office on Apr. 27, 2007, and a Korean PatentApplication Serial No. 2007-56836, which was filed in the KoreanIntellectual Property Office on Jun. 11, 2007, the content of each ofwhich is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a Frequency Division MultipleAccess (FDMA)-based wireless communication system, and in particular, toa method and apparatus for transmitting and receiving Channel SoundingReference Signals (CS RS).

2. Description of the Related Art

Recently, in mobile communication systems, intensive research has beenconducted on Orthogonal Frequency Division Multiple Access (OFDMA) orSingle Carrier-Frequency Division Multiple Access (SC-FDMA) as a schemesuitable for high-speed data transmission in wireless channels.

Presently, the OFDM and SC-FDMA technologies are applied in the downlinkand uplink of the Evolved UMTS Terrestrial Radio Access (EUTRA) standardbased on Universal Mobile Telecommunication Services (UMTS) defined bythe 3^(rd) Generation Partnership Project (3GPP).

SC-FDMA, a technology that is based on single-carrier transmission whileguaranteeing orthogonality between multiple access users like OFDM, isadvantageous in that a Peak-to-Average Power Ratio (PAPR) oftransmission signals is very low. Therefore, SC-FDMA, when it is appliedto the mobile communication system, can bring improvement of the cellcoverage due to its low PAPR, compared to the OFDM technology.

FIG. 1 illustrates a structure of a general SC-FDMA transmitter and aslot structure, in which Fast Fourier Transform (FFT) 103 and InverseFast Fourier Transform (IFFT) 105 are used.

Referring to FIG. 1, a difference between OFDM and SC-FDMA will beconsidered in terms of the transmitter structure. Aside from IFFT 105used for multi-carrier transmission in an OFDM transmitter, FFT 103further exists in front of the IFFT 105 in an SC-FDMA transmitter. Here,M modulation symbols 100 constitute one block, and the block is input tothe FFT 103 with a size M. Each of the blocks will be referred to hereinas a ‘Long Block (LB)’, and 7 LBs constitute one 0.5-ms slot 102.

Signals output from the FFT 103 are applied to the IFFT 105 as inputshaving consecutive indexes (See 104), where the signals undergo inverseFourier transform, and then are converted into an analog signal (See106) before being transmitted. An input/output size N of the IFFT 105 isgreater than an input/output size M of the FFT 103. The SC-FDMAtransmission signal has a lower PAPR than the OFDM signal because thesignal processed by means of the FFT 103 and IFFT 105 has single-carriercharacteristics.

FIG. 2 illustrates exemplary resource partitioning in the frequency-timedomain in a EUTRA SC-FDMA system.

Referring to FIG. 2, a system bandwidth 201 is 10 MHz, and a total of 50Resource Units (RUs) 202 exist in the system bandwidth 201. Each RU 202is composed of 12 subcarriers 203, can have 14 LBs 204, and is a basicscheduling unit for data transmission. The 14 LBs 204 constitute one1-ms subframe 205.

FIG. 3 is a diagram illustrating resource allocation for transmission ofa control channel and a data channel in the EUTRA uplink based on theresource partitioning structure of FIG. 2.

Referring to FIG. 3, control information, such as ACKnowledge(ACK)/Negative ACK (HACK) representative of response signals for aHybrid Automatic Repeat reQuest (HARQ) operation for downlink data andChannel Quality Indication (CQI) representative of channel stateinformation for downlink data scheduling, is transmitted through the RUslocated in both ends, i.e., RU#1 and RU#50 of the system band.Meanwhile, information such as data, Random Access CHannel (RACH) andother control channels, is transmitted through the RUs located in themiddle 302 of the system band, i.e., all RUs except for RU#1 and RU#50.

Control information transmitted in the first slot 308 of RU#1 isrepeatedly transmitted through RU#50 311 in the next slot by frequencyhopping, thereby obtaining frequency diversity gain. Similarly, controlinformation transmitted using the first slot 309 of RU#50 is repeatedlytransmitted through RU#1 310 in the next slot by frequency hopping.Meanwhile, several control channels are transmitted in one RU afterundergoing Code Domain Multiplexing (CDM).

FIG. 4 illustrates the detailed CDM structure for control channels.

Referring to FIG. 4, ACK CHannel (ACKCH)#1 and ACKCH#2 allocated todifferent terminals transmit their associated ACK/NACK signals using thesame Zadoff-Chu (ZC) sequence at every LB. Symbols of a ZC sequence 412applied to ACKCH#1 are transmitted in an order of s₁, s₂, . . . , s₁₂ atevery LB, and symbols of a ZC sequence 414 applied to ACKCH#2 aretransmitted in an order of s₃, s₄, . . . , s₁₂, s₁, s₂. That is, the ZCsequence applied to ACKCH#2 is cyclic-shifted from the ZC sequence ofACKCH#1 by 2 symbols (Δ (Delta)=2 symbols). ZC sequences havingdifferent cyclic shift values ‘0’ 408 and Δ (Delta) 410 according to theZC sequence characteristics having mutual orthogonality. By setting adifference between the cyclic shift values 408 and 410 to a valuegreater than the maximum transmission delay of a wireless transmissionpath, it is possible to maintain orthogonality between channels.

Corresponding ZC sequences of ACKCH#1 and ACKCH#2 are multiplied byACK/NACK symbols b₁ and b₂ desired to be transmitted at every LB,respectively. Due to the orthogonality between the ZC sequences, eventhough ACKCH#1 and ACKCH#2 are transmitted at the same time in the sameRU, a base station's receiver can detect the ACK/NACK symbols b₁ and b₂of two channels without mutual interference. At LBs 405 and 406 locatedin the middle of a slot, Reference Signals (RSs) for channel estimationare transmitted during detection of the ACK/NACK symbols. Like thecontrol information of ACKCH#1 and ACKCH#2, the RS is also transmittedafter undergoing CDM by means of its corresponding ZC sequence. In FIG.4, b₁ and b₂ are repeated over several LBs, in order to enable even theterminal located in the cell boundary to transmit an ACK/NACK signal ofsufficient power to the base station.

According to a similar principle, even the CQI channel transmits onemodulation symbol at every LB, and different CQI channels can undergoCDM using ZC sequences having different cyclic shift values.

FIG. 5 illustrates a structure where five control channels 500˜504 aremultiplexed in one RU for a 0.5-ms slot.

Referring to FIG. 5, there are shown two ACK Channels, ACKCH#1 500 andACKCH#2 501, employing coherent modulation; and three control channelsof Non-Coherent Signaling Control CHannels (NCCCH)#1 502, #2 503 and #3504 for transmitting 1-bit control information using a non-coherentmodulation scheme. ACKCH#1 500 and ACKCH#2 502 transmit RS signals forchannel estimation at the 2^(nd) and 6^(th) LBs (hereinafter, “RS LBs”)511 and 512 (513 and 514), respectively, and transmit ACK/NACK symbols515 at the remaining LBs (hereinafter, “control information LBs”).NCCCHs 502, 503 and 504 transmit only the control information at the1^(st), 3^(rd), 4^(th), 5^(th), and 7^(th) LBs.

ACKCH#1 500 and ACKCH#2 501 apply the same cyclic shift value Δ (shiftof ZC) 510 to ZC sequences transmitted at each LB. Therefore, the samecyclic shift value Δ (shift of ZC) 510 is applied between the twochannels 500 and 501 even at LBs 511˜514 for transmission of RS signals.

For orthogonal detection of ACK/NACK symbols b₁ and b₂ transmitted inthe two channels 500 and 501, the signals multiplexed to ZC sequences ofACKCH#1 500 and ACKCH#2 501 are multiplied by sequence symbols of N-bitorthogonal sequences S_(m,n) 516 (where n denotes a sequence symbolindex, for n=1, . . . , N) with different indexes m in units of LBs. Forinstance, a Fourier sequence defined as Equation (1) can be applied asthe orthogonal sequence.

$\begin{matrix}{{S_{m,n} = {\exp \left( {j\frac{2\pi \; {mn}}{N}} \right)}},{n = 1},\ldots \mspace{14mu},N} & (1)\end{matrix}$

The Fourier sequence satisfies mutual orthogonality between sequenceswith different indexes m, and N=5 in the structure shown in FIG. 5.Aside from the Fourier sequence, other 5-bit sequences such as ZC andGeneralized Chirp-Like (GCL) sequences can also be used as theorthogonal sequence.

In the example of FIG. 5, symbols of 5-bit sequences with indexes 1 and2 are sequentially multiplied by signals of control information LBs ofACKCH#1 and ACKCH#2, respectively. Specifically, at LB 520, each symbolof a ZC sequence applied in common to ACKCH#1 and ACKCH#2 is multipliedby an ACK/NACK symbol b₁ of ACKCH#1 and the first symbol S_(1,1) of aFourier sequence #1. Similarly, at LB 521, each symbol of the ZCsequence is multiplied by an ACK/NACK symbol b₂ of ACKCH#2 and the firstsymbol S_(1,1) of a Fourier sequence #2.

Meanwhile, since two RS LBs 511˜514 exist in one slot, 2-bit Walshsequences with different indexes are applied to ACKCH#1 500 and ACKCH#2501 at RS LBs 511˜514. When ZC sequences with the same cyclic shiftvalue 510 are applied to ACKCH#1 500 and ACKCH#2 501 as described above,since a length of the orthogonal sequence S_(m),_(n) is 5, three moreorthogonal sequences are available. However, as stated above, since onlytwo LBs capable of transmitting the RS exist in one slot, there is aproblem in that it is not possible to generate additional RS signalsother than ACKCH#1 500 and ACKCH#2 501 when applying the same ZCsequences to the control information LBs.

SUMMARY OF THE INVENTION

An aspect of the present invention is to provide a method and apparatusfor transmitting CS RS in a wireless communication system,

Another aspect of the present invention is to provide a method andapparatus for multiplexing CS RS and other uplink control channels in anSC-FDMA-based wireless communication system.

Another aspect of the present invention is to provide a method andapparatus for maintaining the constant resource allocation bandwidth ofCS RS regardless of the amount of resources for other uplink controlchannels thereby to fixedly allocate CS RS to each terminal in anSC-FDMA-based wireless communication system.

Another aspect of the present invention is to provide an ACK/NACKchannel structure for multiplexing a CS RS channel and an ACK/NACKchannel such that a slot where the CS RS is transmitted and a slot wherethe CS RS is not transmitted have the same ACK/NACK channel transmissioncapacity.

In accordance with an aspect of the present invention, a method isprovided for transmitting uplink control information by a terminal in acellular communication system. The method includes receiving systeminformation associated with uplink transmission of a Sounding ReferenceSignal (SRS) from a base station; determining an orthogonal sequencehaving a first length or a second length predefined; transmitting uplinkcontrol information to which a first orthogonal sequence is applied, ifthe first orthogonal sequence having the first length is determined; andtransmitting uplink control information to which a second orthogonalsequence is applied, if the second orthogonal sequence having the secondlength is determined. The SRS is selectively transmitted with the uplinkcontrol information, based on the received system information, and theuplink control information, to which the first orthogonal sequencehaving the first length is applied, is transmitted regardless of whetheror not the SRS is transmitted in a corresponding slot.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentinvention will become more apparent from the following detaileddescription when taken in conjunction with the accompanying drawings inwhich:

FIG. 1 illustrates a structure of a general SC-FDMA transmitter and aslot structure;

FIG. 2 illustrates exemplary resource partitioning in the frequency-timedomain in a EUTRA SC-FDMA system;

FIG. 3 is a diagram illustrating resource allocation for transmission ofa control channel and a data channel in the EUTRA uplink based on theresource partitioning structure of FIG. 2;

FIG. 4 illustrates the detailed CDM structure for control channels; FIG.5 illustrates a structure where five control channels are multiplexed inone RU for a 0.5-ms slot;

FIG. 6 illustrates typical multiplexing of a channel sounding channeland other channels;

FIG. 7 illustrates multiplexing of a CS RS channel and other channelsaccording to a preferred embodiment of the present invention;

FIG. 8 illustrates an example where ACK/NACK channels using a ZCsequence, to which one same cyclic shift value is applied, aremultiplexed in one LB according to an embodiment of the presentinvention;

FIG. 9 is a flowchart illustrating a transmission operation of aterminal according to an embodiment of the present invention;

FIG. 10 illustrates multiplexing of a CS RS channel and other channelsaccording to another embodiment of the present invention; and

FIG. 11 is a diagram illustrating a wireless communication system,according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Various embodiments of the present invention will now be described indetail with reference to the annexed drawings. In the followingdescription, descriptions of known functions and configurationsincorporated herein have been omitted for clarity and conciseness. Termsused herein are defined based on functions in the present invention andmay vary according to users, operators' intention, or usual practices.Therefore, the definition of the terms should be made based on contentsthroughout the specification.

Although a description of the present invention will be made herein withreference to an OFDM-based wireless communication system, especially tothe 3GPP EUTRA standard, the present invention can be applied to othercommunication systems having a similar technical background and channelformat with a slight modification without departing from the scope ofthe present invention.

Referring to FIG. 11, a diagram illustrates a wireless communicationsystem, according to an embodiment of the present invention. A terminal1102 is in communication with a base station 1104. The terminal 1102includes a transmitter 1106 for transmitting signals to the base station1104, a receiver 1108 for receiving signals from the base station 1104,and a controller 1110 for controlling functions of the terminal 1102.The base station 1104 includes a transmitter 1112 for transmittingsignals to the terminal 1102, a receiver 1114 for receiving signals fromthe terminal 1102, and a controller 1116 for controlling functions ofthe base station 1104.

An aspect of the present invention is to multiplex a Channel SoundingReference Signal (CS RS) channel and an uplink control channel in awireless communication system. A CS RS, which is a pilot signal that abase station receives from each terminal, is used by the base station inestimating a channel state from each terminal till the base station.Based on the estimation result, the base station determines a datachannel of which terminal it will schedule, for every subframe. For a CSRS channel, each terminal can have a different transmission bandwidthand a different transmission period according to the terminal state.

The present invention provides a technology for transmitting a CS RS atthe time completely separated from the transmission time of other uplinkchannels, including data and control channels, and matching a bandwidthof allocated resources to the entire uplink system bandwidth (300 inFIG. 3), thereby preventing influence on the number of control channelstransmittable in control channel resources 308, 309, 310 and 311 in theuplink. In addition, the present invention differently applies a lengthof an orthogonal sequence applied to a control channel, i.e., anACK/NACK channel, in a slot where the CS RS is transmitted and a slotwhere the CS RS is not transmitted, thereby enabling transmission of thesame number of ACK/NACK channels in the two slots regardless of whetherthe control channel and CS RS exist in the same slot.

A detailed description will now be made of a CS RS transmissiontechnology provided by the present invention through the followingembodiments.

An embodiment of the present invention does not overlap a CS RS in RUsfor transmitting an uplink control channel, and according thereto, usesone of LBs that the control channel do not use, for the CS RStransmission. In this case, an orthogonal sequence is applied to anACK/NACK channel according to the number of LBs for ACK/NACK bittransmission, remaining after being applied to the CS RS.

FIG. 6 illustrates typical multiplexing of a channel sounding channeland other channels.

Referring to FIG. 6, an uplink system band 601 is composed of N firstRUs 602 and M second RUs 603, all of which are used as controlchannel(s), and a central band between the first and second RUs 602 and603. In EUTRA, ACK/NACK symbols are transmitted using four LBs, and RSis transmitted using three LBs in control channel slots 608, 609, 610and 611.

As illustrated, a CS RS channel 600 can be multiplexed with other uplinkchannels. The CS RS channel 600 is disposed in the first LB interval ofthe central band to which a data channel 605 is mapped. CS RSstransmitted by several terminals undergo CDM using cyclic shifting of ZCsequences, or are multiplexed to different frequency resources.

Generally, the number of uplink RUs 602 and 603 used for control channeltransmission can vary for every subframe according to the number ofnecessary control channels. In that case, in the CS RS multiplexingstructure shown in FIG. 6, a transmission bandwidth of the CS RS channel600 should change for every subframe according to the number of controlchannel RUs 602 and 603 in use so that a band of the CS RS channel 600should not overlap with the band occupied by the control channels, whichprevents interference from occurring between the CS RS channel 600 andthe control channels.

For this reason, in order for the transmission bandwidth of the CS RSchannel 600 to change, it is necessary that terminals transmitting CSRSs must continuously receive, from the base station, signalinginformation on a band of the CS RS channel to be applied in thecorresponding subframe. In addition, it is necessary that CS RS channelsof various bandwidths should be defined. In this case, multiplexing a CSRS from each terminal is complicated, causing a load of determining CSRS sequences of various lengths. Accordingly, there is a need to solvethis problem.

FIG. 7 illustrates multiplexing of a CS RS channel and other channelsaccording to a preferred embodiment of the present invention.

Referring to FIG. 7, an uplink system band 701 is composed of N firstRUs 706 and M second RUs 707, all of which are used as controlchannel(s), and a central band 705 between the first and second RUs 706and 707. A data channel is mapped to the central band 705. ACK/NACKsymbols for an ACK/NACK channel or CQI symbols for a CQI channel aretransmitted in control channel slots 708 and 709 (710 and 711) of thecontrol channel RUs 706 and 707, respectively.

Here, in one subframe 703 composed of two slots 720 and 721, a CS RSchannel 700 is allocated resources over the entire system band 701 ofthe uplink during the first LB 713 regardless of the number of RUs 706and 707 used for transmission of uplink control channels. Therefore, thetransmission bandwidth of the CS RS channel 700 can be maintainedconstant in the subframe 703 regardless of the number of RUs 706 and 707used for transmission of control channels. Accordingly, the systemindicates the band and transmission period to be used as a CS RS channelfor each terminal, and each terminal periodically transmits CS RS usingthe indicated resources without the need to receive additional signalingfrom the base station.

Therefore, the present invention can satisfy the single-carriertransmission characteristic required for SC-FDMA transmission even whena terminal should simultaneously transmit CS RS and a control channel inan arbitrary subframe. In addition, the present invention differentlyapplies a length of an orthogonal sequence applied to an ACK/NACKchannel in a slot where CS RS is transmitted and a slot where CS RS isnot transmitted, thereby enabling transmission of the same number ofACK/NACK channels in the two slots regardless of multiplexing of CS RS.

Among the LBs constituting the first slot 720, one LB is not used for acontrol channel as shown by reference numeral 712, and since uplinkcontrol channels are transmitted while undergoing frequency hopping fora 1-ms subframe as described above, it is necessary that the same numberof control channels can be transmitted in the control channel slots 709and 710. Similarly, even in the control channel slots 708 and 711, thesame number of control channels should be transmitted. An uplinkACK/NACK channel structure for satisfying such requirements will bedescribed below.

FIG. 8 illustrates an example where ACK/NACK channels using a ZCsequence, to which one same cyclic shift value is applied, aremultiplexed in one LB according to an embodiment of the presentinvention.

Referring to FIG. 8, S3_(i,j) denotes a j^(th) sample of a 3-bitorthogonal sequence having an i^(th) index, and S4_(i,j) denotes aj^(th) sample of a 4-bit orthogonal sequence having an i^(th) index. Theorthogonal sequences S3_(i,j) and S4_(i,j) are used for transmission ofACKCH#i in the first slot 720 and the second slot 721, respectively.

For the first slot 720, since CS RS is transmitted at the first LBinterval 806 as described in FIG. 7, a 3-bit orthogonal sequenceS3_(i,j) is used in the first slot in order to maintain orthogonalitybetween ACKCH#1-3. For this purpose, a 3-bit Fourier sequence can beapplied as the orthogonal sequence.

Meanwhile, a 3-bit sequence W_(i,j) is used as a CS RS for channelestimation of ACKCH#i. Since the LB where the sequence W_(i,j) istransmitted is not punctured by the CS RS, positions of the LB are equalin the first slot 720 and the second slot 721. When the CS RS istransmitted at an arbitrary LB in a subframe as stated above, since theLB where the CS RS is transmitted cannot be used for control channeltransmission, the number of LBs for ACK/NACK symbols and LBs for RStransmission, except the LB for transmission of the CS RS, which is setto be equal in both slots.

By proposing the ACK/NACK channel structure shown in FIG. 8, the numberof ACK/NACK channels that can undergo coherent transmission can bemaintained at three channels regardless of the transmission of the CS RSin the corresponding subframe.

Although an index of a sequence for ACKCH#i used in the first slot 720and the second slot 721 does not change in this embodiment, whensequence hopping is applied between slots for inter-cell interferencediversity, an index of a sequence used between the two slots can changefor one ACK/NACK channel, and the index change is not limited in thepresent invention.

Although a description of an embodiment of the present invention hasbeen made herein for a case where a CS RS is transmitted at the first LBof the first slot in a subframe, the present invention is not limited tothe position of the CS RS channel. However, by providing that the LB ofan ACK/NACK symbol is punctured in the slot where the CS RS istransmitted and the number of LBs where the CS RS is transmitted isequal between two slots, the number of transmittable ACK/NACK channelscan be equal in the slot where the CS RS is transmitted and the slotwhere the CS RS is not transmitted. An example of this case will bedescribed with reference to FIG. 9.

FIG. 9 is a flowchart illustrating a transmission operation of aterminal according to a preferred embodiment of the present invention.

Referring to FIG. 9, in step 900, a terminal generates an ACK/NACKsymbol according to a success or failure in decoding of data receivedover a data channel in the downlink. In step 901, the terminaldetermines whether there are any LBs where a CS RS can be transmitted,in a subframe for transmitting the ACK/NACK symbol. The determinationcan be achieved from system configuration information or upper layersignaling information for uplink channels.

If it is determined in step 901 that there is no LB where the CS RS canbe transmitted in the subframe for transmitting the ACK/NACK symbol, theterminal maps in step 902 the ACK/NACK symbol or RS symbols to all LBsin the subframe according to a predefined pattern. In step 903, theterminal applies an orthogonal sequence with a length predefined foreach slot to the mapped ACK/NACK symbol or RS symbols, and then proceedsto step 906. For example, when four ACK/NACK symbol LBs and three RSsymbol LBs exist in one slot as in the second slot 721 of FIG. 8, a4-bit orthogonal sequence S4_(i,j) can be applied to the four ACK/NACKsymbol LBs and a 3-bit orthogonal sequence W_(i,j) can be applied to thethree RS symbol LBs as shown in FIG. 7. In this case, for a high-speedterminal, a 2-bit orthogonal sequence can be applied twice to the fourACK/NACK symbol LBs.

However, if it is determined that there is an LB where the CS RS can betransmitted in the subframe for transmitting the ACK/NACK symbol, theterminal punctures, in step 904, the ACK/NACK symbol allocated to the LBwhere the CS RS exists, does not map the ACK/NACK symbol allocated tothe LB where the CS RS exists, and maps the ACK/NACK symbol or RS symbolto the remaining LBs in the subframe according to a predefined pattern.This process is as shown in the first slot 720 in FIG. 7. In step 905,the terminal applies, to the slot, an orthogonal sequence having alength reduced by the number of punctured symbols for the ACK/NACKsymbol punctured as in the first slot 720, and applies an orthogonalsequence with a normal or a predefined length (sequence for ACK/NACK) tothe ACK/NACK symbol or RS symbol of the unpunctured slot, and thenproceeds to step 906, i.e., the orthogonal sequence applied in step 905is determined according to the number of LBs remaining after beingapplied to the CS RS.

In step 906, the terminal applies a ZC sequence to the ACK/NACK symbolor RS symbol, as shown in FIG. 4, and then transmits the ACK/NACK symbolor RS symbol.

FIG. 10 illustrates multiplexing of a CS RS channel and other channelsaccording to another preferred embodiment of the present invention.

Referring to FIG. 10, an uplink system band 1010 is composed of N firstRUs 1001 and M second RUs 1002, all of which are used as controlchannel(s), and a central band 1011 between the first and second RUs1001 and 1002. A data channel 1012 is mapped to the central band 1011.ACK/NACK symbols for an ACK/NACK symbols or CQI symbols for a CQIchannel are transmitted in the control channel RUs 1001 and 1002.

A difference between the multiplexing structure shown in FIG. 10 and themultiplexing structure shown in FIG. 7 is in that a CS RS transmissionband 1000 does not overlap with transmission bands 1001 and 1002 for anuplink control channel such as ACK/NACK channel and CQI channel.However, as in FIG. 7, in an LB 1005 where a CS RS is transmitted, theACK/NACK symbol and the CQI symbol are not transmitted in the bandsindicated by reference numerals 1003 and 1004. By transmitting the CS RSonly in the band of a data channel in this way, it is possible toprevent the power loss which may occur as the CS RS is transmitted evenin the band of the uplink control channel, i.e., it is possible toimprove estimation accuracy of channel state information for schedulingthe uplink data channel.

As is apparent from the foregoing description, the present invention cansatisfy the single-carrier transmission characteristic required forSC-FDMA transmission even when one terminal must simultaneously transmita CS RS channel and a control channel in one subframe. That is, thepresent invention allows the CS RS channel and the control channel to beindependently transmitted in the SC-FDMA system, so that each terminalcan always transmit each channel whenever needed while satisfying thesingle-carrier transmission characteristic. The base station receivesthe CS RS channel and control channels from each terminal at apredetermined time, thereby scheduling a data channel to each terminalboth in the uplink and downlink at the right time, i.e., at thecorresponding timing, and thus contributing to an improvement of thesystem performance.

While the present invention has been shown and described with referenceto certain embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present invention asdefined by the appended claims.

What is claimed is:
 1. A method for transmitting uplink controlinformation by a terminal in a cellular communication system, the methodcomprising the steps of: receiving system information associated withuplink transmission of a Sounding Reference Signal (SRS) from a basestation; determining an orthogonal sequence having a first length or asecond length predefined; transmitting uplink control information towhich a first orthogonal sequence is applied, if the first orthogonalsequence having the first length is determined; and transmitting uplinkcontrol information to which a second orthogonal sequence is applied, ifthe second orthogonal sequence having the second length is determined,wherein the SRS is selectively transmitted with the uplink controlinformation, based on the received system information, and wherein theuplink control information, to which the first orthogonal sequencehaving the first length is applied, is transmitted regardless of whetheror not the SRS is transmitted in a corresponding slot.